Nelson Pass B-1 preamp kit

wushuliu · « **Reply #140 on:** 24 Mar 2010, 09:51 pm »

Quote from: earplay on 24 Mar 2010, 09:46 pm

Well, maybe it is a capacitor, but it looks like a resistor to me. It's color coded like a resistor.

I'm using the ebay kit. There is no other component that fits the layout. I'm dizzled!

Ok, C2 is for the power supply cap, but you must be referring to R1. This is for a 1 ohm 3 watt resistor.

Can you post a pic of your board?

wushuliu · « **Reply #141 on:** 24 Mar 2010, 09:53 pm »

Quote from: earplay on 24 Mar 2010, 09:46 pm

Well, maybe it is a capacitor, but it looks like a resistor to me. It's color coded like a resistor.

I'm using the ebay kit. There is no other component that fits the layout. I'm dizzled!

also, it is not polarized.

earplay · « **Reply #142 on:** 24 Mar 2010, 09:56 pm »

Yeah, that's it! It's easily seen in avionic's post on page 5. It's the grey resistor on the far right.

earplay · « **Reply #143 on:** 24 Mar 2010, 09:58 pm »

Maybe my batteries are too large... too powerful. I'm just guessing.

wushuliu · « **Reply #144 on:** 24 Mar 2010, 10:01 pm »

Quote from: earplay on 24 Mar 2010, 09:58 pm

Maybe my batteries are too large... too powerful. I'm just guessing.

The B1 can handle up to 40v I believe. Are you sure the batteries are wired correctly? A pic would be aaawful helpful!

sondale · « **Reply #145 on:** 24 Mar 2010, 10:05 pm »

Quote from: wushuliu on 24 Mar 2010, 10:01 pm

The B1 can handle up to 40v I believe. Are you sure the batteries are wired correctly? A pic would be aaawful helpful!

Totally agree - pictures always help.

earplay · « **Reply #146 on:** 24 Mar 2010, 10:14 pm »

The batteries are wired in series.

(neutral) > (-/+) > (-/+) > (load in)

No cam handy.

wushuliu · « **Reply #147 on:** 24 Mar 2010, 10:47 pm »

Quote from: earplay on 24 Mar 2010, 10:14 pm

The batteries are wired in series.

(neutral) > (-/+) > (-/+) > (load in)

No cam handy.

and the + is wired correctly, right? (+ is closest to R1 resistor)

regardless, you should replace the resistor with a decent one from digikey, etc. there's a link on the first page BOM.

earplay · « **Reply #148 on:** 24 Mar 2010, 11:02 pm »

Running out to the local Rat Shack now. Will report back asap!

earplay · « **Reply #149 on:** 24 Mar 2010, 11:35 pm »

Rat Shack no got. Further events must await digikey. Will report when I can. Thanks for everything.

earplay · « **Reply #150 on:** 25 Mar 2010, 03:04 pm »

My bad! Thanks to all who tried to help me, but I fear I may be beyond help.

I looked at my battery connections in the morning light and found that I had reversed + and -. This resulted in the neutral side of the B1 receiving 18v and, I presume, cooking the 1ohm, 3watt resistor and who knows what else.

I couldn't get the digikey site to work correctly so I moved on to Mouser and ordered three 1ohm, 3watt resistors. They are Vishay Dale so the quality is assured. If I smoke them, then I'll know it was me... again!

So, a quick question: would reversing the power cause the resistor to smoke?

earplay · « **Reply #151 on:** 29 Mar 2010, 06:53 pm »

Okay, the new 1ohm, 3watt Vishay-Dale resistor arrived today. I soldered it in and turned on the power.This time the led glowed, but no smoke was emitted. A good sign, but when I installed the preamp into the system, it remained silent. No hum, hiss or pop from either channel.

Now, I'm thinking something else is cooked. I guess I'll have to get out the multi-meter and read the instructions... if I can still find them.

Any ideas for likely suspects?

sondale · « **Reply #152 on:** 29 Mar 2010, 08:55 pm »

Quote from: earplay on 29 Mar 2010, 06:53 pm

Okay, the new 1ohm, 3watt Vishay-Dale resistor arrived today. I soldered it in and turned on the power.This time the led glowed, but no smoke was emitted. A good sign, but when I installed the preamp into the system, it remained silent. No hum, hiss or pop from either channel.

Now, I'm thinking something else is cooked. I guess I'll have to get out the multi-meter and read the instructions... if I can still find them.

Any ideas for likely suspects?

Most likely suspects are the active devices i.e. the 2SK170 (370) and the zener diode, try the zener first - it is the cheapest to replace.

One thing - if you have a DMM do not connect the buffer to your system without checking the dc levels on the outputs of the B1 - better safe than sorry.

earplay · « **Reply #153 on:** 29 Mar 2010, 10:44 pm »

I tested the zener diode. That took a bit of doing, but found a site on using DMM's that was helpful to me, a rank beginner.

Now, I believe I have a problem with the diode because I get a reading in both directions. Not a null or 1 reading, but something up in the high hundreds.

I presume that this kind of reading in both directions indicates a problem. Is this right?

Don't know how to test a jfet, yet. Can someone direct me to a site that would tell me how to do that process? I'm willing to try to learn!

UPDATE: Replaced the zener diode and checked all solder joints. Still no sound of any kind.

Are the jfet's next?

walkern · « **Reply #154 on:** 1 Apr 2010, 03:51 pm »

Hey Earplay...

This may be a really rude question, but since the board comes with no instructions, and the provider does not include a switch, nor does he label the board where the input selector switch would go, I'm wondering if you found a switch on your own and made all the necessary connections to route each input to the active sectons of the board? The Pass boards all have the same accommodations for the input selector switch, and if you don't connect it then there is no way any input signal actually makes it to the active sections of the board.

Just a thought. And if you've already connected the switch, and you are still getting no output, please accept my apologies for questioning your skills. No offense intended.

Neil

earplay · « **Reply #155 on:** 1 Apr 2010, 04:28 pm »

walkern,

Not rude at all! I'm laughing at myself, anyhow. Thanks for the suggestion. I was trying my wings on the Chinese B1 before I went the American route. In other words, I mean to build a second Pass pre as you suggest. Great minds, I suppose.

I'll add this for everyone's amusement. sondale has been holding my hand from across the pond and guiding me through my troubles. It seems that the Chinese kit, in fact, does not include all the board components to make this thing work. The connection of a dpdt switch is necessary. So I learned from sondale and, I think, that fact is mentioned earlier in this thread. This morning, I ran out and got a dpdt switch. It has six leads, 3x2. The board has six holes, 3x2. So, I just connected the three leads from each side to the three leads on each side of the board. What did I get? I get the left channel in position one, I get the right channel in position two. They sound great individually, but I hope sondale doesn't give up on me.

Lance

walkern · « **Reply #156 on:** 1 Apr 2010, 06:26 pm »

Quote from: earplay on 1 Apr 2010, 04:28 pm

walkern,

Not rude at all! I'm laughing at myself, anyhow. Thanks for the suggestion. I was trying my wings on the Chinese B1 before I went the American route. In other words, I mean to build a second Pass pre as you suggest. Great minds, I suppose.

I'll add this for everyone's amusement. sondale has been holding my hand from across the pond and guiding me through my troubles. It seems that the Chinese kit, in fact, does not include all the board components to make this thing work. The connection of a dpdt switch is necessary. So I learned from sondale and, I think, that fact is mentioned earlier in this thread. This morning, I ran out and got a dpdt switch. It has six leads, 3x2. The board has six holes, 3x2. So, I just connected the three leads from each side to the three leads on each side of the board. What did I get? I get the left channel in position one, I get the right channel in position two. They sound great individually, but I hope sondale doesn't give up on me.

Lance

Hey... at least you've got SOUND! Now all you gotta do is figure out how the heck that switch should be wired in and everything will be hunky dunky. Good luck.

Neil

earplay · « **Reply #157 on:** 1 Apr 2010, 07:03 pm »

Neil,

Yeah, I've got sound, true enough. That tells me some things are right. I'm stuck with a partial system. sondale it trying to help me. I may be beyond hope, here.

How complicated can the switch wiring be? I mean, two rows of three on the board, two rows of three on the switch. One to one correspondence. I can figure that out! But, nooooooo! When wired the way that makes sense, it doesn't work correctly. Is there something wrong with the board?

The switch is wired up as I described, so that's a given. It plays, so that's a given. Both channels play, so that's a given. They don't play simultaneously, so that's a given.

ebag4 · « **Reply #158 on:** 1 Apr 2010, 07:13 pm »

It certainly sounds as if you have the switch wired incorrectly. Typically a DPDT switch will wire something like this:

Left input 1------- --------Right Input 1
Common to Buffer Left------- --------Common to Buffer Right
Left input 2------- --------Right Input 2

Your symptoms sound like you either hav the common and input swopped on one side or you have the two inputs swopped on one side.

Good luck!
Ed

sondale · « **Reply #159 on:** 1 Apr 2010, 07:25 pm »

Quote from: ebag4 on 1 Apr 2010, 07:13 pm

It certainly sounds as if you have the switch wired incorrectly. Typically a DPDT switch will wire something like this:

Left input 1------- --------Right Input 1
Common to Buffer Left------- --------Common to Buffer Right
Left input 2------- --------Right Input 2

Your symptoms sound like you either hav the common and input swopped on one side or you have the two inputs swopped on one side.

Good luck!
Ed

I think it is the board - if you look at the left/right inputs for 1 the left goes to the bottom pin on S100 and the right goes to the top pin of S200!

Alan